The present invention relates generally to optical switching, and more particularly to an optical switching system and apparatus using fixed and movable mirrors.
An optical switch is used to switch optical signals between a number of optical inputs and a number of optical outputs.
An optical switch can be formed using two arrays of micro-machined mirrors, which are often referred to as Micro Electromechanical System (MEMS) arrays. Each MEMS array typically includes N mirrors. The MEMS arrays are typically positioned opposite each other. Such an optical switch is generally capable of switching optical signals from any of N input fibers to any of N output fibers.
In order to switch an optical signal from a selected input fiber to a selected output fiber, the optical signal is directed from the selected input fiber to a selected mirror on one MEMS array, which reflects the optical signal to a selected mirror on the other MEMS array, which reflects the optical signal toward the selected output fiber. Input fiber collimators are used to direct optical signals from the input fibers to the first MEMS array. Output fiber collimators are used to direct optical signals from the second MEMS array to the output fibers.
Such optical switches are typically complex and expensive. This is due in part to the cost and complexity of the fiber collimators and MEMS arrays that make up the optical switch.
In accordance with one aspect of the invention, an optical switching system and apparatus uses a fixed mirror cover to reflect optical signals to and from movable mirrors that are formed on a common substrate.
In accordance with another aspect of the invention, an Nxc3x97N optical switching system includes a substrate having a surface including a plurality of input fiber collimators, a first plurality of movable mirrors, a second plurality of movable mirrors, and a plurality of output fiber collimators, and also includes a mirrored cover positioned facing said surface for directing optical signals from the plurality of input fiber collimators to the first plurality of movable mirrors, from the first plurality of movable mirrors to the second plurality of movable mirrors, and from the second plurality of movable mirrors to the plurality of output fiber collimators.
Each input fiber collimator is typically positioned relative to the mirrored cover so as to direct an optical signal from an input fiber to a predetermined mirror of the first plurality of mirrors via the mirrored cover. The mirrored cover may include an angled portion for directing the optical signals from the input fiber collimators to the first plurality of mirrors. The mirrored cover may include a curved portion for directing the optical signals from the input fiber collimators to the first plurality of mirrors. Each input fiber collimator may be set at a predetermined angle relative to the substrate so as to direct the optical signal to the predetermined mirror of the first plurality of mirrors via the mirrored cover. An input optical wedge may be positioned between the plurality of input fiber collimators and the mirrored cover for directing optical signals from the plurality of input fiber collimators to the first plurality of movable mirrors via the mirrored cover.
Each mirror of the first plurality of mirrors is positioned relative to the mirrored cover and to the second plurality of mirrors so as to direct an optical signal to a selected mirror of the second plurality of mirrors via the mirrored cover.
Each mirror of the second plurality of mirrors is positioned relative to the mirrored cover and to the plurality of output fiber collimators so as to direct an optical signal to a predetermined output fiber collimator via the mirrored cover. The mirrored cover may include an angled portion for directing the optical signals from the second plurality of mirrors to the plurality of output fiber collimators. The mirrored cover may include a curved portion for directing the optical signals from the second plurality of mirrors to the plurality of output fiber collimators. Each output fiber collimator may be set at a predetermined angle relative to the substrate so as to receive the optical signal from the predetermined mirror of the second plurality of mirrors via the mirrored cover. An output optical wedge may be positioned between the mirrored cover and the plurality of output fiber collimators for directing optical signals from the second plurality of movable mirrors to the plurality of output fiber collimators via the mirrored cover. Each output fiber collimator is substantially positioned so as to receive the optical signal from the predetermined mirror of the second plurality of mirrors via the mirrored cover axially.
The mirrored cover may be substantially flat. The mirrored cover may be angled toward the substrate at both ends. The mirrored cover may be curved toward the substrate.
The movable mirrors are typically controlled electronically. The optical switching system typically includes control logic for determining a desired position for each movable mirror and generating control signals for setting each movable mirror to its desired position.
In one embodiment of the invention, the optical switching system is configured as a 2xc3x972 optical switch having a pair of input fiber collimators, a first pair of movable mirrors, a second pair of movable mirrors, and a pair of output fiber collimators. The input fiber collimators, movable mirrors, and output fiber collimators may be configured linearly on the substrate. The substrate may include two adjacent collimator/mirror configurations, where each collimator/mirror configuration includes one input fiber collimator from the pair of input fiber collimators, one movable mirror from the first pair of movable mirrors, one movable mirror from the second pair of movable mirrors, and one output fiber collimator from the pair of output fiber collimators.
In another embodiment of the invention, the optical switching system is configured as plurality of Nxc3x97N optical switches. The substrate includes a plurality of Nxc3x97N optical switching configurations, wherein each Nxc3x97N optical switching configuration comprises an equal number of input fiber collimators from the plurality of input fiber collimators, movable mirrors from the first plurality of movable mirrors, movable mirrors from the second plurality of movable mirrors, and output fiber collimators from the plurality of output fiber collimators.